Loud speaker construction



Aug. 3, 1965 .1. w. WQODS 3,198,283

LOUD SPEAKER CONS TRUCTION Filed Nov. 9, 1962 2 Sheets-Sheet l INVENTOR.

JOHN w.wo'o0s BY ZZZ/MW ATTORNEYS 1965 J. W. woons 3,198,283

LOUD SPEAKER CONSTRUCTION Filed NOV. 9, 1962 2 Sheets-Sheet 2 INVENTOR. JOHN W. WOODS BY WMW ATTORNEYS United States Patent 3,198,283 LOUD SPEAKER CONSTRUCTION John W. Woods, Auburn, Caliii, assignor to Sierra Spun Metals, Inc., Auburn, Calif., a corporation of California Filed Nov. 9, 1962, Ser. No. 236,621 1 Claim. (Cl. 18132) This invention relates to loud speakers and cones for such speakers.

In the conventional loud speaker, a sound producing transducer is arranged to impart vibrations to a cone structure, the cone being the device which converts the mechanical vibrations to movements of masses of air to create sound. Conventional speaker cones have been formed of paper cardboard and other relatively pliable, soft materials having some degree of memory. It is important furthermore in the construction of loud speaker cones that a conical or semiconical configuration be formed to produce adequate frequency responses and linearity in audio reproduction.

It has also been found in loud speakers that irregular deformations of the cone structure can cause either a reduction in frequency response or distortion. For this reason, relatively soft materials were thought to be required to provide adequate speaker cones. The softer materials however, quite frequently will deteriorate under certain conditions such as for example in conditions of high humidity, extreme temperatures, and in atmospheres of rapidly varying pressures, such as in areas where explosions of one type or another are likely to occur. Environmental weather conditions and ambient vibrations such as occur in mobile speaker installations, such as for example airplanes, boats and automobiles,

cause great deterioration of conventional cone materials.

Often conventional cones must be replaced after six months or a years use in such applications.

It is the principal object of this invention to provide a speaker cone formed ofan integral section of metal foil being entirely seamless throughout its entire structure and formed in configurations generally analogous to the shapes and designs found suitable for paper and other soft materials. The metallic structure because of its integral composition and seamless structure will withstand many of the variations of ambient conditions which would be very destructive to conventional cone materials. The metal cone, for example, can Withstand high temperatures and is virtually unaffected by moisture and humidity. It is more resistant to the effect of sudden pressure changes such as explosions and is far more resistant to ambient vibrations. The cone furthermore has the unexpected advantage of providing frequency responses and linearity of audio reproduction not only equal to that obtainable from comparable cones formed of conventional materials, but in many cases speakers made in accordance with the teaching of this invention have produced sound in frequency ranges well beyond those obtained from conventional material both at the high and low ranges.

Within the present invention, the cone is generally formed by spinning a flat section of metal foil into the desired conical shape. The spinning process results in compressing the metal in a spiral groove from the peripheral segment of the cone to its central portion. This creates a conical body having small lands and grooves running generally coaxially of the cone metal spinning apparatus constructed generally similarly to the apparatus disclosed in US. Patent No. 2,864,329 issued on December 16, 1958 which has been found particularly adaptable.

The configuration and axis of the lines of metal stress and deformation are believed to contribute to the audio reproduction characteristics of the cone structure. In other types of metal forming, the lines of deformation, compression and bending are normally radially disposed or are disposed in a grain arrangement which will reduce the tendency to create uneven flexibility at different points along common radii throughout the cone structure. In the cone structure of the present invention, the cone ex hibits substantially equal flexibility along any concentric plane.

Another feature and advantage of the invention lies in the fact that the flange portion of the integral component structure can be unworked and exhibits greater flexibility than the cone portion of the structure which has been worked by the spinning process. The greater flexibility of the flange areas provides more flexibility for the cone mounting which is desirable in mounting the cone so it can move forward and backward so it can produce the lower frequencies in sound.

Other objects of the present invention will become apparent upon reading the following specification and referring to the accompanying drawings in which similar characters of reference represent corresponding parts in each of the several views.

In the drawings:

FIGURE 1 is a front this invention.

FIGURE 2 is a cross-section view of FIGURE 1 taken at line 22,

FIGURE 3 is an enlarged fragmentary sectional view of the cone structure showing a forming needle or tool in relationship thereo.

FIGURE 4 is an alternative embodiment of the invention formed to provide sinusoidal concentric deformation in the flange of the cone.

FIGURE 5 shows another embodiment of the invention having a cone formed in a curvilinear configuration.

FIGURE 6- is a still further embodiment of the invention having a generally horned type cone configuration.

Referring particularly to the drawings, the speaker of thisinvention generally comprises a main frame A and a transducer B mounted on the rear of the frame. Cone C is mounted on frame A with its truncated apex 14 being connected directly to transducer 18 with its exterior, annular base flange 15 being mounted on the rim 16 of the frame.

Transducer B is of conventional configuration and is provided with a permanent magnet 18. Piston 21 is axially aligned over the front face 22 of magnet 18 and is supported by a flexible diaphragm 25 which will resiliently hold the piston in alignment for reciprocal movement toward and away from magnet 18. A voice coil winding 28 is wound about piston 21. The terminals 25' of the voice coil are connected to a terminal block 39 mounted on the side wall 31 of frame A. Transducer B operates in the conventional manner in which variations applied on the voice coil through leads 29 vary the electro magnetic force generated by the voice coil which in turn changes the spacing between the piston and the electromagnet so that the piston moves in direct relationship to the electrical power input to the voice coil.

Cone C is formed with a side wall 32 terminating in the truncated apex portion 14 in the form of a flattened axially aligned center diaphraghm 35 and with the exterior annular flange 15 being on the outermost edge. Flange 15 is mounted on rim 16 of frame A and secured thereto by an annular cardboard facing member 40. Annular member 16 and facing member 40 form a sandwich for the flange 15 of the cone so that the entire flange is held completely in a rigid and solid support on the frame.

Diaphragm 35 of the cone is directly connected to piston 21 by a joinder of the center of the diaphragm plan view of a loud speaker of and cone. Thus, reciprocal movement of the piston will generate vibrations in the cone structure.

Cone C is formed by a spinning technique as particularly shown in US. Patent No. 2,864,329. The technique generally involves the employment of a female die having the general configuration of the desired conical structure. A sheet of metal foil is placed over the die. A cutting tool such as indicated at 45 on FIG 3 is then rotated in a helical path against the metal under sufficient pressure to force the metal into the center of the female die as it is rotated through its helical path from the peripheral portion of the cone to the central portion of the cone at 14.v This creates a deformation of metal running annularly in a helix about the central axis of the cone and takes the form of small lands 46 and grooves 47. In the embodiment of FIGS. 1 and 2 the flange 15 is unworked and as such the foil retains its natural softness While the cone body, because of the working of the metal, is rendered considerably harder. This factor is important due to the fact that the flange functions as a hinge to allow reciprocalcone movement for generation of the lower frequencies, while the body of the cone is more rigid and as such is better suited for high frequency sound generations. The resulting cone structure exhibits substantially uniform flexibility throughout the entire cone structure along all planes or cross-sections running transverse the longitudinal axis of the cone the effect of spinning the cone causes the metal of the cone to be thinner and work hardened. As a result, while the characteristics of the cone are changed the flange retains its natural thickness and softness. The thihkness contributes to the durability of the flange so as to prevent fatigue of the metal during use, and the softness allows for the flexture while the cone structure being harder and thinner provides better high frequency reproduction characteristics.

The metal foil employed for the cone structure can be formed of aluminum or like metals and it has been found that aluminum foil in thicknesses between .002 inch and .01 inch are satisfactory for this purpose. It is noted that speakers manufactured in accordance with the teachings set forth herein have exhibited frequency response curves in linearity comparable in every respect to cones formed of conventional materials having identical types of frames and energized by identical types of transducers.

It is noted that the entire cone structure is formed by a single integral seamless sheet of metal with all deforma-' tions in structural characteristics being along lines substantially coaxial with the cones longitudinal axis.

In FIGURE 4 there is provided an alternative embodiment of the invention in which a speaker cone D is formed in the manner substantially identical to that discussed above in relation to FIGURES 1, 2 and 3. Flange 15, however, is formed with pressed sinusoidal shaped annular grooves 50 to impart even greater flexibility in the flange area and to allow the cone structure itself to move in and out reciprocally relative to the frame. The pressing operation can form the metal without substantial increase of hardness from the pressing or working operation. It is pointed out that one of the important features of the cone constructed and used in accordance with the invention lies in the fact that the entire body of the cone wall 32 is worked by the forming needle 45, while the flange 15 is worked only in a way by which the softness of the metal is retained. Thus, in the subject cone construction, the flange area has substantially greater softness and resiliency than the body of the cone itself and is formed with sinusoidal coaxial ribs, This is important for low frequency sound generation. The gross movement of the cone reciprocating generates the low frequency vibrations white the high frequency vibrations are set up by standing waves created by the vibration running along the peripheral wall of the cone itself. Thus, it is the soft cone flange with the sinusoidal or rib construction which creates an efficient hinge. The flange 15 is attached in the em bodiment of FIGURE 4 in the same manner as shown in FIG. 2. The apex of the cone is open and defines a throat 51 which can be connected to piston 28.

in FIGURE 5, there is provided another embodiment of the invention in which the cone is of curvilinear structure having a side Wall 52 having one angle of curvature in which the central portion of the cone is generally formed by a concave wall which gradually becomes convex at 53 to terminate in the flange 55. Such a speaker cone construction is formed in the same way as the forming process indicated in FIGURE 3 in which the flange portion 55 is unworked by the tool 45.

FIGURE 6 is still another embodiment of the cone ructure in which a cone F is formed in a generally hornlike configuration being convex throughout its entire conical wall terminataing in a flat flange 52'. Again the configuration of cone F is formed by the same process as indicated in FIGURE 3.

Although the foregoing invention has been described in some detail by way of illustration and example for purposes of clarity of understanding, it is understood that certain changes and modifications may be practiced within the spirit of the invention as limited only by the scope of the appended claim.

What is claimed is:

A loud speaker of the type having a frame and an energizing means mounted on said frame, the improvement comprising a cone formed of an integral metallic sheet, said cone having a hollow conical body and a radialiy extending rim, the rim of the cone securely fastened to the rim of said frame, and the apex of the conical body attached to said energizing means, the conical body of said cone being work hardened and formed with small closely spaced lands and grooves running in a helix as acquired by metal spinning, said rim being unworked and corrugated in coaxial corrugations as acquired by pressing, whereby the rim of the cone is substantially softer and thicker than the conical body to allow the rim of the cone to function readily as a flexible support for the conical body on the rim of the frame.

References Cited by the Examiner H LEO SMILOW, Primary Examiner.

CHARLES W. ROBINSON, LEYLAND M. MARTIN,

Examiners. 

